The present invention relates to the field of photography and, more specificially, to a photographic copy apparatus or camera for previewing an original picture to be copied (e.g., 35 mm slide transparency) and projecting an enlarged image of the original picture onto a film unit for exposure.
Copy cameras that use self-developing film units for quickly and easily making enlarged prints from 35 mm slide transparencies are well-known in the prior art. For representative examples of these devices, see U.S. Pat. Nos. 2,866,380; 3,065,667; 3,697,175; 3,653,760; 4,082,446; and 4,200,392, along with commonly-assigned copending applications Ser. Nos. 152,744 and 152,858, both filed on May 23, 1980.
The last-mentioned patent and copending applications direct attention to the fact that the 24.times.36 mm image area format of a 35 mm slide (normalized width to height or length, 1.times.1.5) is not compatible on a direct enlargement basis with most standardized self-developing film units or conventional print paper formats which generally fall in a normalized format range of 1.times.1 to 1.times.1.4. For example, a 3.25".times.3.25" self-developing film unit has a normalized format of 1.times.1, while 4.times.5 or 8.times.10 works out to be 1.times.1.25.
When a 35 mm slide image is to be printed on a standard size print paper or self-developing film unit, it is obvious that the projected image must be cropped in the long direction if the entire width of the film is to be used. Conversely, if the full 35 mm frame is to be printed, fitting the long dimension to the film format will result in black borders on the sides of the print because of the narrower normalized width of the slide format.
The copy devices disclosed in the aforementioned U.S. Pat. No. 4,200,392 and copening applications Ser. Nos. 152,744 and 152,858 take the approach that a cropped image which fits the entire print format is generally more aesthetically pleasing and the small loss of image area at the ends of the frame is tolerable in that for the most part it is confined to scene background which is most instances may be eliminated without loss of very much picture information.
However, there are many applications, especially in the technical, industrial, graphic arts and medical fields, where it is also important to be able to reproduce the entire 35 mm frame. Such applications may include providing an 8.times.10 enlargement of a tiny integrated circuit to inspect wire bonds and conductor continuity or reproducing data from the CRT of a CAT scan machine.
Thus, there is a need for a copy camera which can alternately provide either a full frame or cropped reproduction depending on the particular application. To switch between the full frame and cropped modes, there must be a corresponding change in image magnification. For example, to make an 8.times.10 enlargement of a full 35 mm frame, the image magnification factor is approximately 7.3.times. while a full width but shortened length cropped image is produced with an image magnification factor of approximately 9.9.times..
Multiple magnification photographic copy devices, such as enlargers and graphic arts copy cameras, are well-known in the prior art. Because magnification is a function of the ratio of image-to-object distance and the focal length of the projection lens, there are many ways to vary magnification.
For example, if the same lens is to be used for different levels of magnification, then there must be some way to change the ratio of image-to-object distance. In devices using this technique, the object plane is usually fixed, and a lens and film holder are mounted for movement relative to each other and the object plane to adjust image size and focus. This type of structure requires guide rails, bellows, rack and pinion drives, etc., and is inherently expensive. Also, the operator must have some expertise or training to properly operate this equipment. For a representative example of such a device using this approach, see U.S. Pat. No. 3,645,620.
Another technique involves the use of interchangeable lenses or a zoom lens to vary focal length thereby allowing the image and object planes to be at a fixed distance from each other. A representative example of a copy device employing this method is disclosed in U.S. Pat. No. 4,184,763. Again, such a device is inherently expensive because it requires at least two different lenses or a costly zoom lens to change magnification. Also, the operator must be trained to change lenses or adjust the zoom lens.
Therefore, it is an object of the present invention to provide a multiple magnification copy apparatus or camera that is low in cost and easy to use.
It is another object to provide such copy apparatus that is operative to provide either a full frame or cropped reproduction of a 35 mm slide transparency on a film unit of a given format size.
It is yet another object to provide such a copy device wherein the operator may preview the slide and select the area to be cropped.
Another object is to provide such a copy device which includes a system for indicating which one of two different magnification modes has been selected and further includes a system for inhibiting operation when the slide and/or film is not in the correct position for the select level of magnification.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.